SPE Library
The SPE Library contains thousands of papers, presentations, journal briefs and recorded webinars from the best minds in the Plastics Industry. Spanning almost two decades, this collection of published research and development work in polymer science and plastics technology is a wealth of knowledge and information for anyone involved in plastics.
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Conference Proceedings
Production of Plasticizer (Lubricant) from Soya Bean Oil for the Rubber Industry
Chikwado J. Udeokoro, May 2001
Di-2-ethylhexyl phthalate (DOP) has been own to be used as a plasticizer in rubber industries but because of the abundance of soyabean seeds in the world, it has become imperative to study how its oil can be used as a plasticizer in place of the conventional one. From the results epoxidezed soyabean oil has a higher plasticization effect on Nitrile rubber than DOP. An equal plasticization can be achieved by using a ratio of 1:2 soyabean oil epoxide and DOP respectively. Increase in the plasticizer concentration reduced the specific gravity hardness, viscosity, tensile strength, modulus, minimum and maximum torque. However the higher the concentration of the epoxidized soyabean oil, the more the elongation at break.
Design of Experiment: Determining the Effect of Process Parameters on the Weld Line Strength of GPPS & SBC
Jeffrey L. Wilson, May 2001
This study evaluated the effect of melt temperature, injection velocity, and holding pressure on the weld line strength of general-purpose polystyrene (GPPS) and styrene-butadiene copolymer (SBC). Specifically, double gated tensile bars were molded according to the runs required for a three factor, two level ANOVA. The tensile and impact testing results were then analyzed to determine which parameters were significant to the weld line strength. The results show that the tensile data for GPPS were affected by melt temperature only and that the impact results were not affected at all. On the other hand, the tensile results for SBC were influenced by melt temperature, injection velocity and holding pressure while the impact results were affected by melt temperature and injection velocity.
An Investigation of Cavity Pressure Transducer Position when Used for Velocity to Pressure Transfer with Various Injection Molding Process Strategies
Jobe C. Piemme, Michael P. Downey, May 2001
The use of cavity pressure for velocity to pressure transfer during the injection phase of the molding process is generally considered to be the most repeatable method. This study looked at the effect of cavity pressure transducer location and the velocity at which transfer occurs for three different process strategies: 1) transfer before the melt front hits the last place to fill, 2) transfer during the pack phase with the screw going relatively fast, and 3) transfer at the end of pack with the screw going relatively slow. This experiment found that, as long as an inflection point is seen in the cavity pressure curve, it does not matter which cavity pressure transducer location is used when considering process consistency.
Hydrogel Contact Deposition of Polymeric Multilayers
Christophe J. Lefaux, Patrick T. Mather, May 2001
We are pursuing a novel processing method for the rapid processing of polymeric multilayers with spatial resolution for such applications as polymeric photovoltaic devices and microfluidics. Toward this end, hydrogel contact deposition offers a quick and efficient procedure for producing multilayer polymeric structures by combining aspects of both electrostatic self-assembly (ESA) and contact stamping. We are studying the influence of the hydrogel's physical properties on such a process. For the present study, uncharged hydrogel applicators, swollen by two different solutions of polymers (positively and negatively charged), were used for controlled growth of multilayers via cyclic contact. The resulting coating structures were characterized.
Using Crosslinked Polyethylene to Stabilize Metal Injection Molding Feedstock
Alicyn M. Haney, Shawn D. McConaughy, May 2001
Shape retention of Metal Injection Molding (MIM) parts throughout the debinding and sintering stages of production is a common problem throughout the industry. Slumping of parts often causes distortion and diminishes surface detail. Challenges in development of a binder system include powder compatibility, wetability, and polymer compatibility. A mix of coupling agents, surfactants, anti-oxidants, plasticizers and compatibilizers must be determined. The proposed polyethylene based binder system will eliminate the distortion phase encountered by traditional systems. Feedstock must not cure during compounding or injection molding. Sample batches will be compounded and molded. Successful candidates will be tested for shape retention and mechanical properties.
An Experimental Study of the Flow of an Encapsulated Polymer Melt through a Unique Blown Film Die
Joseph Dooley, Steve Jenkins, John Naumovitz, May 2001
Many polymers are extruded through blown film dies to produce monolayer and multilayer films. The most popular style of die in use today to produce blown films is the spiral mandrel die. This type of die can be used effectively for many polymers but cannot easily be used with thermally sensitive materials due to long flow paths and large surface areas that can lead to polymer degradation. This paper will discuss a new, unique blown film die technology in which a thermally sensitive polymer is encapsulated with a less sensitive material and processed into a blown film. Experimental data will be shown on the viscosity of encapsulated melts and the unique flow patterns in the die.
A TriSEC and 3dTREF Approach to Polymer Blend Design
Wallace W. Yau, David Gillespie, May 2001
Polyolefin technology has made remarkable progress in the last four decades. The market is expanding and the technical challenges today remain high. New products are being developed with new catalysts or by the blending processes. New resins are needed to meet the requirements of high-speed fabrication machines, and market expansions into high-tech applications. A successful resin development either by blending or by optimizing catalyst and reactor condition requires a strong polymer characterization support in determining the polymer microstructures. To this end, we have made considerable upgrade of our polymer characterization capabilities using GPC and TREF. Our approaches are the following. First, we have focused on obtaining the best precision we could out of these techniques. We then added the triple detector capabilities to the systems and take a hybrid approach of analyzing the polymer microstructure results. We generated a polymer microstructure plot" that contains both the triple detector GPC and TREF results in one chart. We find the results presented this way are very effective in comparing products or defining blending conditions for resin design."
The Case against Oxidation as a Primary Factor for Bonding Acid Copolymers to Foil
Barry A. Morris, Naozumi Suzuki, May 2001
Oxidation is often used in the extrusion-coating industry to enhance the adhesion of LDPE to polar substrates such as aluminum foil. Previous investigators have suggested that oxidation plays a key role in the adhesion of acid copolymers to foil; the most direct evidence for this is the observed increase in peel strength with increasing time in the air gap (TIAG). The results of new experiments, however, suggest that oxidation may not be responsible for this behavior. Acid copolymers that have been ozone treated, loaded with antioxidants or processed at temperatures well below the expected onset of oxidation still show the characteristic increase in adhesion with increasing TIAG. Measurement of peel strength in the MD and TD show that the TD peel strength is not influenced by TIAG and peel strength correlates with % elongation of the coating. This suggests that stress and orientation may play a role in the observed behavior. A practical implication of this work is that acid copolymers will generally adhere more strongly to foil than LDPE, even when the acid copolymer is processed at lower temperatures. This reduces the potential for taste/odor, processing and other problems associated with high-temperature processing.
A New mLLDPE for Extrusion Coating Applications
Richard W. Halle, Kevin M. Cable, May 2001
Metallocene polyethylenes are well known for providing superior toughness, heat sealing, and clarity versus conventional polyethylenes. Their unique attributes have been employed for almost a decade in the manufacture of many different high-performance blown and cast films for numerous end-use applications. Lower density metallocene plastomers have also found use in specialty extrusion-coated and laminated structures where good puncture and tear resistance along with excellent hot tack and heat sealing performance are required. An extrusion coating study has shown that a similar set of attributes can be obtained using a new mLLDPE. For the best extrusion coating performance, the mLLDPE should be blended with small amounts of LDPE.
Joining of Thermoplastics with Friction Stir Welding
Carl D. Sorensen, Tracy W. Nelson, Seth Strand, Clark Johns, Jason Christensen, May 2001
Friction stir welding is a process that is used for joining aluminum and its alloys. It requires only relatively simple tooling, and is extremely safe. There are no arcs, fumes, or other emissions. Early attempts to use the process for joining plastics were unsuccessful, but newly developed tooling has made it possible to weld many thermoplastic materials using a modified FSW process. This paper reports the tooling and operating parameters used to join a variety of materials, as well as the strengths of the resulting joints. Weld properties in ABS, PP, and HDPE exceeded 90% of the base material strength using the new tooling developed.
Visual Color Evaluations: Problems and Solutions
Bob Trinklein, May 2001
In this era of high-powered computers and spectrophotometers, the human eye-brain combination of a trained observer is still commonly used as a tool to evaluate color differences. This paper is written in hopes of pointing out some of the potential areas for problems with visual observation, and how these can be overcome to allow this wonderful tool to be used effectively. To start with the basics, there are three things necessary to have color-a light source, an object, and an observer. If you remove any of these, color no longer exists. What is equally true but perhaps less obvious is that if you change one of them, the color changes. Change the object, and the color changes-this is quite evident. Change the light source and the color changes-perhaps less evident, but still true. What is the least evident is that if the observer changes, the color changes. This is due to the nature of the way the eye works.
Modeling Structural Recovery: Analysis of the Peak Shift Method
Yong Zheng, Sindee L. Simon, Gregory B. McKenna, May 2001
Amorphous polymers below their glass transition temperature, Tg, are inherently not at equilibrium. As a consequence, their structures continuously relax in an attempt to reach the equilibrium state. Models of structural recovery can quantitatively describe this process. One of the parameters needed in the models is the non-linearity parameter x. It has been purposed that x can be obtained from experimental data using the peak-shift method. In this work, we use computer simulations to quantify the error in the value of x obtained from the peak shift method.
Development of a Continuous Thermal Separation System for the Removal of PVC Contamination in Post-Consumer PET Flake
Robert Dvorak, Edward Kosior, May 2001
Differences in thermal properties of plastics such as their softening and melting points can be exploited to separate mixed post-consumer plastic flake. This form of separation can be most effective if differences in melting or softening points of the two plastics are large. For example polyvinyl chloride (PVC) and polyethylene terepthalate (PET) differ in their softening points by ~ 60°C, (i.e. PVC becomes tacky at 200°C and PET at 260°C. This article examines the development of a rotary thermal separating system for the removal of PVC flake from a stream of post-consumer PET flake.
Advances to Dynamic Mechanical Analysis
Jonathon Foreman, May 2001
Dynamic Mechanical Analysis (DMA) is growing technique for characterizing the modulus and mechanical damping of materials as function of temperature. The technique as it exists today is most important for measurement of the glass transition and sub-glass transitions, the latter of which gives insight into molecular structure. However the technique has not gained wide acceptance among design engineers because the calculated modulus values can only be verified over a limited range. A new instrument that uses a new measurement paradigm is presented. The new measurement system uses a simpler model for converting instrument signals to modulus values for more reliable results. Due to the enhanced measurement system, the range of measurements is also greatly extended. The new instrument uses single differential thermal analysis to provide a means for direct measurement of the specimen temperature through a thermal device in contact with the clamps. SDTA also provides the means to calibrate temperatures using primary melting point materials.
Influence of the San Content in the ABS Terpolymer Toughness and Phase Morphology
Roberto S. Yamakawa, Carlos Alberto F. Correa, Elias Hage Jr., May 2001
Currently toughening mechanisms are relatively well known for rubber toughened plastics. However, brittle polymer toughening by mechanical blending with another toughened plastic still need some understanding. The present work correlates morphology and physical properties for high rubber content ABS and its blends with SAN copolymer. The results indicated a close relationship between interparticle distance and fracture toughness for the blends. An non-inverted phase morphology of the ABS explains deviations in mechanical properties as compared to a conventional ABS.
Influence of Interphase Characteristics on Mechanical Properties of Polypropylene/Glass Fiber Composites with PP-g-MAH Interfacial Compatibilizer
Paulo E. Lopes, José A. De Sousa, May 2001
The mechanical properties of glass fiber-reinforced polypropylene are strongly influenced by the type and degree of interfacial interactions attained, depending on the efficiency of the coupling agent used in the composite. In order to modify the fiber-polymer interfacial interactions, composites of PP with aminosilane-treated GF were prepared using PP-g-MAH as interfacial compatibilizer. The superior tensile and impact properties obtained in these composites can be attributed to improved fiber-polymer adhesion achieved by a thicker and more deformable interphase formed with PP-g-MAH concentration.
Determination of the Kinetics Crystallization Constant in a Heterophasic Polypropylene Using the Master Curve Approach
Alessandra Lucas Marinelli, Benjamim de Melo Carvalho, Rosario E.S. Bretas, May 2001
The purpose of the present work was to test the validity of the Master Curve Approach to determine the nonisothermal crystallization rate constant for a heterophasic polypropylene. Nonisothermal crystallization experiments were carried out in a DSC at several cooling rates, being the original curves corrected for the temperature lag between the sample and the furnace. The relative crystallinity as a function of temperature were simulated using the Nakamura equation and the determined kinetic constant. A relatively good agreement with the experimental curves was obtained.
Powerful Gearboxes for Plastics Extrusion Especially in the US Market - A Market Study
Rolf Doebereiner, Frank-Michael Funk, May 2001
In the manufacturing process of plastic, extruders are commonly utilized. In addition to the relatively simple built single screw extruders, twin-screw extruders with co- or counter-rotating screws are used. The drive unit (motor and gearbox) it is the most important unit besides the screws and the barrel of the extruder, and is essentially influencing product quality and product output. During the last years the possible plastics output of these machines increased strongly. In a similar way, the demands towards the screws and cylinders increased as well as towards the gearboxes with regard to power, respectively torque / speed and output. To design such high-torque and/or high-speed drive units in an economic way, extraordinary experience and the use of the up-to-date results from research is required from the manufacturer of gearboxes. One further main demand on the gear is to achieve similar torsion stiffness of the two output shafts in order to hold the difference in torsion angle between the screws small. Differing rotation angles would lead to modifications in the screw gap, which directly influences the product quality. In the following, technical solutions for high-torque and high-speed gearboxes are explained and compared. For this they are put on a common technical basis.
Commercialization of Microcellular Blow Molding
Ritchie Straff, Jere Anderson, Kent Blizard, Brian Chapman, May 2001
Microcellular processing techniques have been applied at a commercial level to both extrusion and injection molding plastics processing, using the patented and proprietary development of Trexel, Inc. The results have been quite successful. In extrusion, the MuCell® microcellular process has allowed the reduction of weight of typical extrusion products by up to 25%, and increases in productivity, while maintaining excellent physical properties. In injection molding, the same basic processing techniques have provided molders with the ability to produce parts with reduced warpage, greater dimensional accuracy, at lower molding pressures and at faster cycle times. All this combined with weight reduction in these parts.
Film Finishing Part I: Commercial and Emerging Thermoplastic Film Based Technologies
Thomas M. Ellison, May 2001
The Automotive Finishing Industry, valued at $2.3 billion in North America1, is faced with serious challenges to reduce cost and a growing urgency to meet environmental pressures. The industry is making major progress to reduce emissions but more must be done as requirements are tightened. Concurrently, other technologies are being advanced that may radically change the finishing process in the long term. Finishing plastic parts with film is one of the emerging technologies. Film finishing presents an opportunity for the Plastics Industry to step forward with an all-plastic solution - plastic film finishes on reduced weight plastic body panels.
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